Dear All, I have a somewhat similar question. We tested my daughter titter at 2,5 years and it was 600, we have just tested it again at 4,5 and it is at 216. I am really worried about the fact that it is dwindling. My other child is consistently at over 1000 and she is almost 3 now. Both were vaccinated at birth, 1 month, and 6 months. Passive and active vaccination. I am really anxious and ask myself why we didnt test hbs ag level. I know they typically do not co-exist, but I am very worried.
Dear @Natti,
It sounds like you are doing the right thing by your children and they are well protected from Hep B.
It is natural that circulating antibody levels taper off over time. However, these are just a marker for the broad panel of antiviral immunity that you have. The B-cells that produce antibody over time will turn into “memory” B-cells - they go into a sleeping state and to be activated straight away when the body sees the virus again. It is likely that your children are still protected, given the generally accepted level for protection is 10 mIU/mL.
Hope this helps!
Thomas
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Thank you very much! This is very helpful. So it is normal that they dwindle in one child and do not seem to budge in the other or my partner?
Hi Natti
I am not a virologist or immunologist but I’ve studied immunity in med school and the titer is something that is not exactly the same level for everyone even in twins there are dozens of factors that can affect the titer the only thing that doctors care about is the cut level for hbv it’s 10 mIU/mL this is the level that is protective against HBV infection however even levels below 10 doesn’t exclude immunity but rather we are not sure if its 100% protective
both your child response is very well people who are reactive are those above >10mIU/mL
yours are even stronger >100 mIU/mL that’s being said they have dozens of antibodies it’s really hard for a virion to escape that numbers of antibodies circulating the blood and it will be the case for several years it will take time for them to get levels down 10 mIU/mL so the bottom line be relieved and not to be worried
As mentioned by @Mohammed_Yassin, there are definitely differences in vaccine response amongst people: some respond with very high levels of antibody, while others will take multiple goes for them to respond with enough antibodies to be protective.
I think in the case of your child constantly at >1000, this may be the limit of the test. So if there is a reduction, it may be that it is not observable because it is still over the upper limit of the assay. Most people’s antibody levels will reduce over time after a vaccination.
Hope this helps,
Thomas
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